carburetor to air filter housing seal

I've seen it dozens of times. The air filter rubber mount is broken, the air filter to valve cover nut is missing, the filter housing wind nut is gone..... any one (or more) of those situations cause the air filter housing to vibrate and wear out this seal that goes between it and the carb. 

If it's missing you'll never get a proper seal and you can let dirt into the carb. You don't want that. 

Fits 81-89 carbureted.